A CL65 crew, on descent to dca, encountered extreme turbulence at approximately FL180.

Attributes
ACN	565936
Time
Date	200211
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dca.airport
State Reference	DC
Altitude	msl single value : 18000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 240 flight time total : 4600 flight time type : 3000
ASRS Report	565936
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 175 flight time total : 2300 flight time type : 600
ASRS Report	566382
Events
Anomaly	inflight encounter : turbulence other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : regained aircraft control
Consequence	faa : reviewed incident with flight crew other other
Supplementary
Problem Areas	Weather
Primary Problem	Weather

Narrative:

During descent around 20 mins from dca at approximately FL180, flight encountered extreme turbulence. The aircraft was impossible to control for approximately 5 seconds. Aircraft control was re-established and the flight continued safely to dca. Before the encounter, only light with occasional moderate turbulence was experienced. Since the flight was within 30 mins to dca, the first officer had already made the required cabin announcement to the passenger. In addition, the first officer made a call directly to the flight attendant to remain seated for her safety due to the turbulence. The flight attendant notified the pilots that several passenger had received injuries. In response, operations was called by the first officer to request medical assistance at the gate. 8 passenger were taken to the hospital, 2 removed by backboard by crash fire rescue equipment. Supplemental information from acn 566382: during the turbulence, the CL65 experienced a maximum bank angle of 45 degrees and a pitch change of 30 degrees. The seatbelt sign was on and the aircraft was written up with maintenance for extreme turbulence.

Original NASA ASRS Text

Title: A CL65 CREW, ON DSCNT TO DCA, ENCOUNTERED EXTREME TURB AT APPROX FL180.

Narrative: DURING DSCNT AROUND 20 MINS FROM DCA AT APPROX FL180, FLT ENCOUNTERED EXTREME TURB. THE ACFT WAS IMPOSSIBLE TO CTL FOR APPROX 5 SECONDS. ACFT CTL WAS RE-ESTABLISHED AND THE FLT CONTINUED SAFELY TO DCA. BEFORE THE ENCOUNTER, ONLY LIGHT WITH OCCASIONAL MODERATE TURB WAS EXPERIENCED. SINCE THE FLT WAS WITHIN 30 MINS TO DCA, THE FO HAD ALREADY MADE THE REQUIRED CABIN ANNOUNCEMENT TO THE PAX. IN ADDITION, THE FO MADE A CALL DIRECTLY TO THE FLT ATTENDANT TO REMAIN SEATED FOR HER SAFETY DUE TO THE TURB. THE FLT ATTENDANT NOTIFIED THE PLTS THAT SEVERAL PAX HAD RECEIVED INJURIES. IN RESPONSE, OPS WAS CALLED BY THE FO TO REQUEST MEDICAL ASSISTANCE AT THE GATE. 8 PAX WERE TAKEN TO THE HOSPITAL, 2 REMOVED BY BACKBOARD BY CFR. SUPPLEMENTAL INFO FROM ACN 566382: DURING THE TURB, THE CL65 EXPERIENCED A MAX BANK ANGLE OF 45 DEGS AND A PITCH CHANGE OF 30 DEGS. THE SEATBELT SIGN WAS ON AND THE ACFT WAS WRITTEN UP WITH MAINT FOR EXTREME TURB.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.